package service

import (
	dao "assets/dao/asset"
	dto "assets/model/dto/asset"
	entity "assets/model/entity/asset"
	"context"
	"errors"

	"gitea.com/red-future/common/db/gfdb"
	"github.com/gogf/gf/v2/database/gdb"
	"github.com/gogf/gf/v2/util/gconv"

	"github.com/gogf/gf/v2/frame/g"
)

const (
	// DefaultPathSeparator 路径分隔符
	DefaultPathSeparator = "/"
)

// CategoryService 分类服务
type CategoryService struct{}

var Category = new(CategoryService)

// Create 创建分类
func (s *CategoryService) Create(ctx context.Context, req *dto.CreateCategoryReq) (res *dto.CreateCategoryRes, err error) {

	// 构建分类路径和层级
	parent, err := dao.Category.GetOne(ctx, &dto.GetCategoryReq{Id: req.ParentId})
	if err != nil {
		return nil, err
	}
	if g.IsEmpty(parent) {
		return nil, errors.New("父分类不存在")
	}
	req.Path = parent.Path + DefaultPathSeparator + gconv.String(req.ParentId)
	req.Level = parent.Level + 1

	err = gfdb.DB(ctx).Transaction(ctx, func(ctx context.Context, tx gdb.TX) error {
		var id int64
		req.IsLeafNode = gconv.PtrBool(true)
		if id, err = dao.Category.Insert(ctx, req); err != nil {
			return err
		}

		// 更新父节点的 IsLeafNode 为 false
		if err = s.updateLeafNode(ctx, req.ParentId, false); err != nil {
			return err
		}

		res = &dto.CreateCategoryRes{
			Id: id,
		}

		return nil
	})

	return
}

// updateLeafNode 更新分类的 IsLeafNode 字段
func (s *CategoryService) updateLeafNode(ctx context.Context, categoryId int64, isLeaf bool) (err error) {
	_, err = dao.Category.Update(ctx, &dto.UpdateCategoryReq{
		Id:         categoryId,
		IsLeafNode: &isLeaf,
	})
	return
}

// GetOne 获取单个分类
func (s *CategoryService) GetOne(ctx context.Context, req *dto.GetCategoryReq) (*dto.GetCategoryRes, error) {
	one, err := dao.Category.GetOne(ctx, req)
	if err != nil {
		return nil, err
	}
	res := new(dto.GetCategoryRes)

	if err = gconv.Scan(one, &res); err != nil {
		panic(err)
	}

	return res, err
}

// List 获取分类列表
func (s *CategoryService) List(ctx context.Context, req *dto.ListCategoryReq) (*dto.ListCategoryRes, error) {
	list, total, err := dao.Category.List(ctx, req)
	if err != nil {
		return nil, err
	}
	res := &dto.ListCategoryRes{Total: total}
	err = gconv.Struct(list, &res.List)
	if err != nil {
		return nil, err
	}
	return res, nil
}

// GetTree 获取分类树
func (s *CategoryService) GetTree(ctx context.Context, req *dto.GetCategoryTreeReq) (*dto.GetCategoryTreeRes, error) {
	list, _, err := dao.Category.List(ctx, &dto.ListCategoryReq{
		Keyword: req.Name,
	})
	if err != nil {
		return nil, err
	}
	tree, err := s.buildTree(ctx, list, 0)
	if err != nil {
		return nil, err
	}
	return &dto.GetCategoryTreeRes{Tree: tree}, nil
}

// buildTree 构建树形结构
func (s *CategoryService) buildTree(ctx context.Context, categories []entity.Category, parentId int64) ([]*dto.CategoryTreeNode, error) {
	tree := make([]*dto.CategoryTreeNode, 0)
	for _, cat := range categories {
		if !s.isChildOf(cat.ParentId, parentId) {
			continue
		}
		node, err := s.convertToTreeNode(ctx, &cat, categories)
		if err != nil {
			return nil, err
		}
		tree = append(tree, node)
	}
	return tree, nil
}

// isChildOf 判断分类是否为指定父节点的子节点
func (s *CategoryService) isChildOf(childParentId, parentId int64) bool {
	if g.IsEmpty(childParentId) && g.IsEmpty(parentId) {
		return true
	}
	if g.IsEmpty(childParentId) || g.IsEmpty(parentId) {
		return false
	}
	return childParentId == parentId
}

// convertToTreeNode 将分类实体转换为树节点
func (s *CategoryService) convertToTreeNode(ctx context.Context, category *entity.Category, allCategories []entity.Category) (*dto.CategoryTreeNode, error) {
	res := new(dto.CategoryTreeNode)
	if err := gconv.Struct(&category, &res); err != nil {
		return res, err
	}
	children, err := s.buildTree(ctx, allCategories, category.Id)
	if err != nil {
		return res, err
	}
	res.Children = children
	res.IsLeafNode = len(children) == 0
	return res, nil
}

// hasChildren 检查分类是否有子分类
func (s *CategoryService) hasChildren(ctx context.Context, parentId int64) (bool, error) {
	count, err := dao.Category.Count(ctx, &dto.ListCategoryReq{
		ParentId: parentId,
	})
	return count > 0, err
}

// updateLeafNodeIfNoChildren 如果父分类没有子分类了，更新为叶子节点
func (s *CategoryService) updateLeafNodeIfNoChildren(ctx context.Context, parentId int64) error {
	hasChildren, err := s.hasChildren(ctx, parentId)
	if err != nil {
		return err
	}
	return s.updateLeafNode(ctx, parentId, !hasChildren)
}

// UpdateStatus 更新分类状态
func (s *CategoryService) UpdateStatus(ctx context.Context, req *dto.UpdateCategoryStatusReq) (err error) {
	var updateReq *dto.UpdateCategoryReq
	if err = gconv.Struct(req, &updateReq); err != nil {
		return
	}
	_, err = dao.Category.Update(ctx, updateReq)
	return
}

// Update 更新分类
func (s *CategoryService) Update(ctx context.Context, req *dto.UpdateCategoryReq) error {
	oldCategory, err := dao.Category.GetOne(ctx, &dto.GetCategoryReq{Id: req.Id})
	if err != nil {
		return err
	}
	err = gfdb.DB(ctx).Transaction(ctx, func(ctx context.Context, tx gdb.TX) error {
		if rows, err := dao.Category.Update(ctx, req); err != nil && rows > 0 {
			return err
		}

		// 如果修改了父分类，需要更新相关节点的 IsLeafNode
		if s.parentIdChanged(req.ParentId, oldCategory.ParentId) {
			if !g.IsEmpty(req.ParentId) {
				if err = s.updateLeafNode(ctx, req.ParentId, false); err != nil {
					return err
				}
			}
			if !g.IsEmpty(oldCategory.ParentId) {
				if err = s.updateLeafNodeIfNoChildren(ctx, oldCategory.ParentId); err != nil {
					return err
				}
			}
		}
		return nil
	})

	return err
}

// parentIdChanged 判断父分类是否发生变化
func (s *CategoryService) parentIdChanged(newParentId, oldParentId int64) bool {
	if g.IsEmpty(newParentId) && g.IsEmpty(oldParentId) {
		return false
	}
	if g.IsEmpty(newParentId) || g.IsEmpty(oldParentId) {
		return true
	}
	return newParentId != oldParentId
}

// Delete 删除分类
func (s *CategoryService) Delete(ctx context.Context, req *dto.DeleteCategoryReq) error {
	// 检查是否有子分类
	hasChildren, err := s.hasChildren(ctx, req.Id)
	if err != nil {
		return err
	}
	if hasChildren {
		return errors.New("该分类下有子分类，无法删除")
	}

	// 检查是否有资产
	if count, err := dao.Asset.Count(ctx, &dto.ListAssetReq{
		CategoryId: req.Id,
	}); err != nil {
		return err
	} else if count > 0 {
		return errors.New("该分类下有资产信息，无法删除")
	}

	// 获取分类信息用于后续操作
	category, err := dao.Category.GetOne(ctx, &dto.GetCategoryReq{Id: req.Id})
	if err != nil {
		return err
	}
	err = gfdb.DB(ctx).Transaction(ctx, func(ctx context.Context, tx gdb.TX) error {
		// 删除分类
		if rows, err := dao.Category.Delete(ctx, req); err != nil && rows > 0 {
			return err
		}

		// 如果删除的是叶子节点，更新父节点为叶子节点
		if !g.IsEmpty(category.ParentId) {
			return s.updateLeafNodeIfNoChildren(ctx, category.ParentId)
		}
		return nil
	})

	return nil
}